First, "Refined Learning" in the Imperium tech tree. This is a repeatable technology, that I think is supposed to increase all tech research by 10%. This tech does nothing. Kingdoms have a similarly placed and named tech called "Refined Education", that does work.
Second, Empire has a tech called "Superior Mining", which implies that it should unlock a smelter building. I have quoted the text.
The only sources of metal in the world at this point are the various metal deposits. To make the best use of them, we can construct smelters. This technology will enable said construction.
There is no such building for empire. Indeed, this tech does not give me access to such a building. Kingdoms have a similarly named and placed technology called "Smelting" that does give access to such a building. In addition, Kingdoms also have access to "Blacksmithing", a direct follow-up on "Smelting", unlocking another building called Blacksmith that also increases metal production.
